Thermal relay



Dec. 1, 1970 I I D S 3,544,941

THERMAL RELAY Filed Nov. 26. 1968 IN VE N 70/? orro [M /swa BY UnitedStates Patent U.S. Cl. 33738 12 Claims ABSTRACT OF THE DISCLOSURE Athermal relay with one or more operating coil phases. The actuatingmembers associated with the coil phases are of bimetallic strips tocompensate for dimensional variation due to thermal effects. Eachoperating phase has a movable sliding member cooperating with theactuating member. Electrical contracts are actuated through the slidingmovable members in their path of motion. Each one of the sliding movablemembers is provided with a spring portion in the form of an archterminating in a projection which is movable upon a sliding surface.This sliding surface lies upon a projection, in turn, of a retainingmember in which the sliding movable members are slidable. A contactactuating link with a U-shaped portion is arranged relative to thesliding surface so that the U-shaped portion becomes contacted by thespring portion after sliding off the sliding surface.

BACKGROUND OF THE INVENTION The present invention resides in a thermalrelay with one, two or more phases associated with actuating elements.These elements grip a slider Which actuates electrical operatingcontacts through motion along a predetermined path, depending upon theoperating current.

Thermal relays of the preceding species are known in the art. Theseconventional relays, however, are exceptionally complex in design andconstruction, and are not reliable in operation.

Accordingly, it is an object of the present invention to avoid thesedisadvantageous features. This object of the present invention isachieved by providing that each movable member is constructed with aspring portion associated with a sliding surface along a pathcorresponding to the operating current. A movable element is arranged onthe sliding surface so that the spring portion of each movable memberstrikes the electrical operating contact with this element after leavingthe sliding surface.

An advantageous design of the present invention resides in the design ofa spring portion of the movable member, so that this spring portionpresses upon the movable element as a result of the force of the cooloperating element during its return motion. This pressure exerted by thespring portion takes place until this spring portion reaches again itsnormal position upon the sliding surface, after sudden and sharp releasefrom the movable element. Through this design, a considerable advantageis realized through the condition that the energy associated with thecooling bimetallic strip is used to return the operating elements of therelay to their normal or inoperative position. This design saves the useof springs or similar auxiliary means. Heretofore, relays have requiredsuch spring parts, and these had to be pre-stressed during theoperation. Through this design of the relays, heretofore, the bimetallicstrips were consequently subjected to considerable forces which causedthem to become insensitive and operate with poor precision.

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In a simplified construction of the present invention, the movablemembers operate parallel to each other and are all movable within aslide. In this design, it is of advantage to provide the sliding surfacein the form of a projection of the slide. A further embodiment anddesign of the relay of the present invention, the slide is provided witha recess into which the outer free end of a displaceable tongue expandsfor the purpose of regulating the setable region. In this manner, it ispossible to achieve through simple construction, regulation of thesetable region. Thus, the slide and thereby the sliding surface of theprojection of the slide become shifted or moved, and the operation takesplace earlier or later, as desired.

A simplified construction and a particularly advantageous design resultswhen the movable element is in the formof a U-shaped head member whichgrasps with play, the portion containing the sliding surface. Inconjunction with this, it is advantageous that the spring portion ofeach movable member has an arch terminating in a projection parallel tothe sliding surface, and including a reinforcing or supporting member.

In some cases, it is advantageous to construct the thermal relay withprovision for space compensation. This may be achieved in a very simplemanner from the constructional viewpoint, by providing that theoperating elements as well as the tongue are of bimetallic strips whichserve to compensate for spatial or dimensional variations.

In order to overcome insulating problems, the present invention providesfurther that the movable members and/or their spring portions of therelay are made of insulating material. At the same time, the design canbe such that the springs are of metallic substance covered withinsulating material.

In the aforementioned embodiment of the present invention, the forces ofthe associated operational elements of bimetallic substance, are appliedonly in conjunction with the operation. Thus, these forces are notrequired to stress any springs or similar such elements during theoperational process, As a result of this condition of the design of thepresent invention, more than a single contact may be actuated by themovable element. For example, it is possible to actuate an interruptercontact for the protective coil and aside from this, a circuit closurecontact such as a signal contact. These contacts may be actuated at thesame instant of time.

SUMMARY OF THE INVENTION A thermal relay with one or more operating coilphases. Each operating coil phase has an actuating member cooperatingwith a slidable or movable member. An electrical signal contact becomesactuated through the sliding or movable memberin the path of motion ofthe latter. Each sliding or movable member is provided with a springportion terminating in a projection slidable upon a surface whichprojects from a slide. The slide with its sliding surface is positionedas a function of the current through the operating coil. A movableU-shaped member actuates the electrical contact when the spring portionslides off the sliding surface on the slide.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawing.

3 BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a plane view of the thermalrelay, in accordance with the present invention, when in the normalinoperative state;

FIG. 2 is a sectional view taken along the line 11-11 in FIG. 1; and

FIG. 3 is a partial operational view of a portion of the relay in FIG.1, when in the operated state.

DESCRIPTION OF THE PREFERRED EMBODIMENT In referring to the drawing, thediagrams are to be considered from the purely schematic viewpoint indetermining the novel construction and features of the thermal relay, inaccordance with the present invention. Thus, the individual relay partsare shown only in schematic form for the purpose of permitting a clearerunderstanding. It will be apparent that when producing a miniaturizeddesign or a simplified design, the relevant steps may be taken withregard to the construction of the parts.

In the embodiment schematically shown, a base plate 1 is provided with asimple and fixed guide block 2. A slide 3 is held by the guide block andis movable to the left or right in relation to the fixed guide block.The slide 3 has three longitudinal channels 30, 3b and 3c in whichmovable rods or bars 4, 5 and 6 are lengthwise retained. Throughopenings 7a, 8a and 9a, the individual movable rods or bars arecontacted with actuating elements in the form of bimetallic strips 7, 8and 9, respectively. These bimetallic strips are provided with coils 10,11 and 12 corresponding to the desired phases. A spring 13 lies at theright end of the slide 3 and abuts the plate 14.

At the left end of the slide 3 is a projection 3d and 3e. The projectionportion 3e has at its upper side a gliding or sliding surface 3f.Between the two projections lies a recess into which the foot 15cprojects. This foot is part of a head portion to be described below.Each movable bar or member 4, 5 or 6 is provided with a spring portion4a in the form of an arch terminating in a projecting portion 4b Whichis parallel to the gliding surface 3 The spring portion 4a, furthermore,is provided with a cross or incline supporting member 4c. The element 32of the projection 3d of the slide has, for example, ane L-shape whenviewed from the top. A U- shaped head member 15a with feet 15b and 15cgrasps the element 3e with play therebetween. The head portion 15a withfeet 15b and 15c are part of the movable member 15. The movable member15 is vertically slidable within the guiding bears 16, and is pressedupward in the normal or inoperative state, by a spring 18. A connectingmember 17, furthermore, connects the movable member 15 with a contact19. Connections 20 and 21 lead to the contact 19. Through the rod 22,one or more additional contacts may be actuated, in operation, as forexample the contact 23 which may be used to advantage as a signalcontact.

The region of the right end of the slide 3 is provided with a recessedportion 24. The outer free end of an adjustable tongue 25 reaches intothe recessed portion 24. The tongue is secured to a rotatable settingarrangement 26 which may be moved or adjusted in either clockwisedirection or counterclockwise direction. As a result of this possibledisplacement of the arrangement 26, the tongue 25 may be displacedeither to the left or to the right within the limits designated by thebroken lines in drawing. The tongue 25 serves the purpose of regulatingthe setting or adjustment region as to be described subsequently. Whenspace compensation is desired, the tongue 25 as well as the operationalmembers 7, 8 and 9 may be constructed of bimetallic strips.

All essential elements of the thermal relay, in accordance with thepresent invention, which are not directly operative with the contacts,are made of insulating material. This applies particularly to the slide3, the movable rodes or bars 4, 5 and 6, and their spring elements 4a,4b and 4c. The aforementioned strip portions can also be constructed ofspring metal with insulating covering.

In operation, when one phase of two phases as, for example, a coils 10and 12, has current exceeding that of the other phase, the bimetallicstrips 7 and 8 become bent. This bending action is such that the upperends of both strips are deflected to the left, and thereby move the rods4 and 5 to the left also. In this action, the projecting element 4bslides to the left on the entire gliding or sliding surface 3 on theportion 3e associated with the projection 3d of the slide. Theprojecting element 4b moves to the left, in this manner, until its edgereaches the left upper edge of the sliding surface 3 At this instant thearch 4a strikes downward with its projection 4b and reinforcing member40, as a result of the spring force inherent in the arch member 4a. Instriking downward, in this manner, the U-shaped head portions 15a, 15band of the movable member 5 are contacted and moved against the actionof the spring 18. Through the motion of the membor 17 moving downwardwith the movable member 15, the contact 19 becomes sharply opened, whilethe contact 23 becomes simultaneously closed as a result of the downwardmovement of the rod 22. During this operation, the bimetallic strip 9retains the slide 3 in its original position, against the action of thespring 13.

After the bimetallic strips 7 and 8 have become cool again, the movablemembers 4 and 5 return or retrace their path, with their spring portion4a as well as the projection 4b. In this motion, the projection 4bslides or glides on the left upper edge of the sliding surface 3 untilthe projection 4b is again on top of the sliding surface 3 Theoperational states of the relay may be determined from a comparison ofFIGS. 1 and 3.

During the last-aforementioned process in which the projection 4b slidesagain on top of the sliding surface 3]", the reinforcing or supportingc-ross member 4c bears steadily on the upper surface of the foot 150,and thereby retains the movable member 15 in its lower or depressedposition. This condition prevails even though the projection 4b has leftcontact with the foot 15b. As a result of the construction of the arch4a with its inherent spring force, the cross member 40 is associatedwith a pressure or force amplification. At the instant, however, whenthe projection 4b reaches over the sliding surface 3 the projectionslides upon the sliding surface to the right and towards its originalposition. During this motion to the right of the projection 4b, thecross member 4c becomes sharply removed from the foot 150, and therebyallows the contact 19 to close again. The closure of the contact 19results from the motion of the member 15 in the upward direction throughthe action of the spring 18. At the same time, the contact 23 isre-opened in view of the upward motion of the rod 22.

The same process prevails when also other phases or all three phasesreceive an excess of current.

It has been found in practice that when the phases are loadedunsymmetrically, rapid disconnection must take place, and the relay asdescribed above, in accordance with the present invention, provides forthis purpose. In this manner the thermal relay of the present inventionprovides for a simple configuration in which a dependable and sensitivedifferential protection is effectively achieved. With symmetrical oruniform loading of the phases, an increased load can result from theconnecting electrical apparatus. The relay, in accordance with thepresent invention, takes this condition also into account in thefollowing manner. When the loading is uniform in the coils 10, 11 and12, the bimetallic strips 7, 8 and 9 are essentially bent uniformlyalso. As a result the slide 3 can be moved somewhat to the left, throughthe action of the spring '13, until the element 25 is reached. With themotion of the slide 3, however, the projection 3:1 is also movedtogether with its portion 3e and the sliding surface 3]. The

left lower edge 4d of the arch 4a thereby passes over the left upperedge 3g of the sliding surface 3 but first at a later instant of time orat a higher current load of the phases. Through this action, theprocedure operation was carried out as described above.

Through the presence of the tongue 25, the thermal relay, in accordancewith the present invention, may be regulated over a wide setable regionto take into account various factors. The upper end of the tongue 25extends into the recess 24 with a substantial amount of play betweenthese two parts. If the tongue is rotated in the clockwise direction,the upper end of the tongue becomes displaced somewhat to the right.With a predetermined bending of the bimetallic strips, it will beunderstood that the right edge of the recess 24 will strike or come incontact with the upper end of the tongue 25. When the upper end of thetongue thus strikes or abuts against the inner wall of the recess 24,the slide 3 is held stationary, and accordingly the action describedabove occurs correspondingly in time. If, on the other hand, the tongue25 is rotated or displaced in the counterclockwise direction, the upperend of the tongue is moved or displaced to the left. The slide isthereby first held stationary by the tongue after a larger slidingmotion to the left. Thus, the movable members 4, 5 and 6 can first incura relative motion With respect to the slide, either individually ortogether, when a corresponding larger current prevails, as describedabove for the current loading. When, in addition, space compensation isdesired for the thermal relay, the tongue 25 may be constructed ofbimetallic strips. With this construction the bimetallatic strip issubjected to the same variation as the bimetallic strips 7, 8 and 9,which result from variations in the temperature of the space. Byresorting to this type of construction, space temperature compensationis achieved.

The present invention is not limited to the embodiment described in thedrawing. The present invention may also be extended and used inconjunction with the principles that have hereinbefore described, sothat the present intion may be adapted to different factors andconditions, as well as the associated constructions.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofconstructions diifering from the types described above.

While the invention has been illustrated and described as embodied inthermal relays, it is not intended to be limited to the details shown,since various modifications and structural changes may be made Withoutdeparting in any way from the spirit of the present invention.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims:

1. A thermal relay comprising, in combination, at least one operatingcoil means; actuating means in proximity of said operating coil meansand operatively coupled with said coil means so that heat transmitted bysaid coil means impinges uponsaid actuating means; sliding meansdisplaced by said actuating means; spring means secured to said slidingmeans; sliding surface means displaceable relative to said spring means,said spring means being movable on said sliding surface means;displacement means for displacing said sliding surface means; a movablemember arranged relative to said sliding surface means and displaced bysaid spring means after sliding off said sliding surface means; andcontact means actuated by said movable member when displaced by saidspring means secured to said sliding means.

2. The thermal relay as defined in claim 1 wherein said sliding meanscomprises a plurality of slidable movable members arranged parallel toeach other.

3. The thermal relay as defined in claim 2 including a slide retainingmember for retaining said slidably movable members, said slidablymovable members being slidable within said slide retaining member.

4. The thermal relay as defined in claim 1 wherein said movable memberhas a U-shaped portion lying opposite said spring means.

5. The thermal relay as defined in claim 1 wherein said spring meanscomprises an arch-shaped portion with a projecting portion parallel tosaid sliding surface means; and a supporting portion secured to saidarch portion.

6. The thermal relay as defined in claim 1 wherein said sliding meansand said spring means are of electrically insulating substance.

7. The thermal relay as defined in claim 1 wherein said spring means isof electrically insulating substance.

8. The thermal relay as defined in claim 1 including electricallyinsulating means on said spring means.

9. The thermal relay as defined in claim 1 wherein said contact meanscomprises a plurality of electrical contacts.

10. A thermal relay comprising, in combination, at least one operatingcoil means; actuating means in proximity of said operating coil meansand operatively coupled with said coil means so that heat transmitted bysaid coil means impinges upon said actuating means; sliding meansdisplaced by said actuating means; a slide retaining member forretaining said sliding means; spring means on said sliding means;sliding surface means displaceable relative to said spring means, saidspring means being movable on said sliding surface means; a movablemember arranged relative to said sliding surface means and displaced bysaid spring means after sliding off said sliding surface means; andcontact means actuated by said movable member when displaced by saidspring means on said sliding means, said sliding surface meanscomprising a projecting portion on said slide retaining member.

11. A thermal relay comprising, in combination, at least one operatingcoil means; actuating means in proximity of said operating coil meansand operatively coupled with said coil means so that heat transmitted bysaid coil means impinges upon said actuating means; sliding meansdisplaced by said actuating means; spring means on said sliding means;sliding surface means displaceable relative to said spring means, saidspring means being movable on said sliding surface means; a movablemember arranged relative to said sliding surface means and displaced bysaid spring means after sliding off said sliding surface means; contactmeans actuated by said movable member when displaced by said springmeans secured to said sliding means, said sliding means comprising aplurality of slidable movable members arranged parallel to each other; aslide retaining member for retaining said slidably movable members, saidslidably movable members being slidable within said slide retainingmember; and a displaceable tongue member having a free end extendinginto a recess of said slide retaining member.

12. The thermal relay as defined in claim 11 wherein said actuatingmeans and said tongue member comprise bimetallic strips for compensatingagainst dimensional changes resulting from thermal effects.

References Cited UNITED STATES PATENTS 2,199,477 5/1940 Besag 337--47XFOREIGN PATENTS 994,436 6/ 1965 Great Birtain 337-49 625,121 1/1936Germany 337335 OTHER REFERENCES German printed application DAS1,128,535, April 1962, Carlsson et al., 337-3 8.

BERNARD A. GILHEANY, Primary Examiner D. M. MORGAN, Assistant ExaminerU.S. Cl. X.R. 33749, 335

